I wanted to make a homemade brake for bending small sheet metal
things. (I have a press). I think that the concept is straightforward,
however, I would like to know if there is any sort of a table that
tabulated bending effort per inch of the width of metal being bent,
depending on thickness.

Also, for the dies, would it be more proper to use high speed steel as
opposed to mild steel (for strength).

Thanks

i

Look for a thread stated by me with a great response from Nick Mueller about
6-12 months ago.

I can't find it on short notice but he suggested a urethane insert similar
to this
http://cgi.ebay.com/1-X-12-URETHANE-...QQcmdZViewItem

only better. Then make everything from plain old cold rolled steel.

Karl

Are you thinking a press brake?
http://www.northerntool.com/webapp/w..._479830_479830

Capacity is heavily dependent on the shape of the dies and especilly the
width. Narrower gives you a sharper bend at the expense of higher
required tonnage and more die wear.

Most of the shop built units I've seen for a 12 or 20 ton shop press use
heavy wall angle iron. Professional press brake dies are all hardened
tool steel. If you could find a 12" section of old press brake die, that
would be perfect.

Keep in mind that the work needs to be perfectly centered under the
cylinder.

Ignoramus24341 wrote:
I wanted to make a homemade brake for bending small sheet metal
things. (I have a press). I think that the concept is straightforward,
however, I would like to know if there is any sort of a table that
tabulated bending effort per inch of the width of metal being bent,
depending on thickness.

Also, for the dies, would it be more proper to use high speed steel as
opposed to mild steel (for strength).

Thanks

i

I have made a couple different sizes of brakes for my 20 ton HF press.
The basic concept is to machine an appropriate vee block for the bottom
and use square bar at 45° for the upper die. You can see what I did at:

http://www.spaco.org/Press.htm

I have bent 90° angles in 5/32" or so thick mild steel, 15 or so inches
wide with the largest brake by bending some, sliding and bending some more.
There's plenty of power left over.

I made my dies from mild steel and they okay for occassional use, but I
do nick them with small parts from time to time when I squeeze real
hard. So, if I had the choice, I'd use 4140 or something like that
next time. I don't think they need to be real hard.

In the third picture down, you can see my biggest brake. In the center
of the vee block, you can just make out the scrapes that I put in it
bending some short, narrow pieces of 1/8" material 2 inches wide, that I
do on a semi-regular basis.

I use the HF air-over hydraulic jack in this machine, and I love it!

Pete Stanaitis
------------------------

Ignoramus24341 wrote:

I wanted to make a homemade brake for bending small sheet metal
things. (I have a press). I think that the concept is straightforward,
however, I would like to know if there is any sort of a table that
tabulated bending effort per inch of the width of metal being bent,
depending on thickness.

Also, for the dies, would it be more proper to use high speed steel as
opposed to mild steel (for strength).

Thanks

i

On 2008-03-06, spaco wrote:
I have made a couple different sizes of brakes for my 20 ton HF press.
The basic concept is to machine an appropriate vee block for the bottom
and use square bar at 45° for the upper die. You can see what I did at:

http://www.spaco.org/Press.htm

Looks great. I will make something like those dies.

I have bent 90° angles in 5/32" or so thick mild steel, 15 or so inches
wide with the largest brake by bending some, sliding and bending some more.
There's plenty of power left over.

How do you like this HF press, just curious.

I made my dies from mild steel and they okay for occassional use, but I
do nick them with small parts from time to time when I squeeze real
hard. So, if I had the choice, I'd use 4140 or something like that
next time. I don't think they need to be real hard.

OK. I have some 4140.

In the third picture down, you can see my biggest brake. In the center
of the vee block, you can just make out the scrapes that I put in it
bending some short, narrow pieces of 1/8" material 2 inches wide, that I
do on a semi-regular basis.

I use the HF air-over hydraulic jack in this machine, and I love it!

I love that jack, also. It is very quiet too.

i

Ignoramus24341 wrote:


How do you like this HF press, just curious.

I've had it for probably 15 years, bought the air-over hyd. jack about
10 years ago and no problems at all.
It does what it is supposed to do.
I guess I say it in the webpage, but adding casters was something I
should have done many years ago,
not just last year. I used to have the press out in a cold area in a
corner, which made it hard to get to and therefore unused when it would
have been the best choice for the job at hand. Now it can be rolled up
to wherever it's needed.
The only thing I'd do differently is to add a pressure gage to the
jack. A guy gave me instructions, but I guess I'm chicken to tear the
jack apart and then have it leak when I'm done. I should do it.
Considering that the things have been on sale for $69.95 recently, life
wouldn't come to a standstill if I failed. 'Spose I could even order a
set of seals before I begin.


I love that jack, also. It is very quiet too.

For me, it's a "no compromises" tool. I don't give up anything to get
the power benefit.

I like the putt-putt. You get used to the rate of the "putts" telling
you how close to full pressure is being exerted.

Pete Stanaitis
---------------------

Mine:
http://www.metalworking.com/dropbox/...retired_files/
see brake1.txt and the associated jpgs.
JR
Dweller in the cellar

Ignoramus24341 wrote:

I wanted to make a homemade brake for bending small sheet metal
things. (I have a press). I think that the concept is straightforward,
however, I would like to know if there is any sort of a table that
tabulated bending effort per inch of the width of metal being bent,
depending on thickness.

Also, for the dies, would it be more proper to use high speed steel as
opposed to mild steel (for strength).

Thanks

i


--
--------------------------------------------------------------
Home Page: http://www.seanet.com/~jasonrnorth
If you're not the lead dog, the view never changes
Doubt yourself, and the real world will eat you alive
The world doesn't revolve around you, it revolves around me
No skeletons in the closet; just decomposing corpses
--------------------------------------------------------------
Dependence is Vulnerability:
--------------------------------------------------------------
"Open the Pod Bay Doors please, Hal"
"I'm sorry, Dave, I'm afraid I can't do that.."

JR North wrote:

Mine:
http://www.metalworking.com/dropbox/...retired_files/
see brake1.txt and the associated jpgs.

Wrong type of brake. He wants a press brake like:

http://www.northerntool.com/webapp/w...70_21896_21896

I made a brake using the HF 20T press & air-over jack. Works well - the
old "I don't need it often, but when I do, it's really nice to have".

- for the male die:
http://home.comcast.net/~bobengelhardt/brake1.jpg

- for the female, I used 1/2" rd bars side by side (the pic is rather
cluttered, sorry):
http://home.comcast.net/~bobengelhardt/brake2.jpg

- the fence is really nice - it can be hard to align your scribed bend
line with the die's edge

- the press's table & arbor were pretty loose. As a plain press that's
fine, but for braking it can be a problem. I installed adjusters to
keep the table and arbor aligned:
http://home.comcast.net/~bobengelhardt/brake3.jpg

As usual, I was motivated to use the material that I had & keep it
simple (e.g., there was no milling involved).

The most-needed improvement is a speed-up for the no-load travel. The
press has to open wide to get the bent piece out and then close up for
the next bend. It's putt-putt-putt- ... . There was a thread where
Ernie modified his jack to do this.

For box bending it would be nice to have a set of long-reach male dies
of various lengths. I do have one shorter die (the one in the brake1
pic). I can do a step-wise box bend (partial bend, move over, repeat),
but it's tedious.

I wasn't used to building for these kind of forces and had to add
reinforcing to the table and more weld generally.

Bob